A generic frothing device is known, for example, from DE 44 45 436 C2, this frothing device having a supply pipe for steam, a supply pipe for air and a supply pipe for milk in a mixing region. The supply pipe for the air is in this case connected to a compressed air source for blowing in air, the blowing in of the air itself being controllable. This is in particular intended to achieve an improved air input at the beginning of the frothing process and consequently improved frothing properties.
In addition to the known frothing device, systems are also known which can also produce and dispense hot milk by switching off an air supply. In this case, however, the temperature is always lower than that of the froth (milk-air mixture) since more mass must be heated in the same time. This is counteracted, for example, by separate devices limiting the milk flow or additionally releasing steam pipes. However, such additional devices require installation space and incur additional costs with the result that, in particular, the requirement for compact and inexpensive equipment can no longer be satisfied. In general, known frothing devices have a number of shortcomings so that, for example, a ratio of air to amount of milk depends on the steam pressure and as a result, an evaluation of the steam pressure and an adaptation of the conveyed amount of air cannot be achieved cost-effectively. Furthermore, a satisfactory frothing result cannot be achieved with the known frothing devices insofar as the air at constant pressure is introduced into the steam pipe with fluctuating pressure. In addition, in cold frothing devices relatively too much air is frequently conveyed in the pipe with the result that a Venturi process does not even get started. This effect is still further exacerbated by the condensate present in the steam pipes.
The present invention is concerned with the problem of providing an improved or at least an alternative embodiment for a frothing device of the generic type in which milk froth having a high temperature and a fine-pored stable consistency or hot milk whose temperature corresponds to that of the milk froth can be produced.